RELATED APPLICATIONS
[0001] This application claims priority to Taiwan Patent Application Serial Number
100145612, filed Dec. 09, 2011, which is herein incorporated by reference.
BACKGROUND
Technical Field
[0002] The present disclosure relates to an illumination controlling circuit. More particularly,
the present disclosure relates to an illumination controlling circuit with dimming
functions.
Description of Related Art
[0003] With recent development of the photonics technology, many cutting-edge illumination
equipments have been introduced to our daily life. For example, comprehensive attentions
have been paid on fluorescent lamps and light-emitting diodes (LED) and their applications.
[0004] Among those equipments, a LED lamp has an efficiency superior to a traditional incandescent
lamp, because most energy consumed by the LED lamp is transformed into a visible radiation.
The LED lamp has a photoelectric conversion efficiency far higher than that of other
lamps, and the LED lamps generates less heat during operation. Therefore, under a
condition of same luminance, the LED lamp with a higher light-emitting efficiency
has a lower operative temperature than that of the traditional incandescent lamp,
such that the LED lamp suitable for the green-energy trend is widely used in all kinds
of illumination applications.
[0005] Traditional incandescent lamps are usually cooperated with a tri-electrode alternating-current
switch (TRIAC) dimmer, which is conveniently for users to adjust luminance of the
incandescent lamps themselves, so as to prevent wasting energy and possible uncomfortable
feelings of eyes due to the over-brightness. In general, the TRIAC may include a variable
resistor, in which a resistance can be adjusted (e.g., with rotating a knob of the
TRIAC) by users. In this way, users are able to control a conductive angel of the
TRIAC, so as to change an output waveform of the TRIAC.
[0006] The dimming function of the TRIAC is realized in a phase-chopping manner. Reference
is made to Fig. 1, which is a schematic diagram illustrating a dimming signal waveform
generated by a tradition TRIAC dimmer. In Fig. 1, the waveform generated by the TRIAC
is chopped according to its phases, and the dimming result is related to the conductive
angle of the phase-chopping.
[0007] However, the LED lamp is a direct current (DC) load unlike the incandescent lamps,
and thus is unable to directly apply the dimming function of the TRIAC. The LED lamp,
directly driven by a waveform adjusted by the TRIAC dimmer, will blinks at a high
frequency. Besides, when the dimming brightness is configured lower, the blinking
becomes more severe. Therefore, an adjustable contrast range of the LED lamp with
the TRIAC dimmer is limited.
[0008] Currently, the commercialized LED equipments utilize specific LED drivers for transforming
household electricity into a fixed DC voltage signal, which is used to drive the light-emitting
component in the LED for illumination. The DC voltage signal is set at a fixed voltage
level. Therefore, the luminance cannot be adjusted easily. In order to keep up with
the green-energy trend and users' demands, there is still a need to develop LED illumination
equipments with practical dimming function.
SUMMARY
[0009] In order to solve the problems in the art, the disclosure provides an illumination
controlling circuit and an illumination system.
[0010] An aspect of the invention is to provide an illumination controlling circuit coupled
between a household electricity input and an illumination lamp. The illumination controlling
circuit includes a dimming module, a sampling-and-holding circuit, a differential
circuit, an integrator circuit and a voltage-clamping circuit. The dimming module
is coupled with the household electricity input. The dimming module is configured
for modulating an alternating current input signal from the household electricity
input and generating a dimming signal. The dimming signal includes a plurality of
waveform pulses. The sampling-and-holding circuit is coupled with the dimming module.
The sampling-and-holding circuit is configured to continuously sample from the waveform
pulses of the dimming signal to obtain an average waveform pulse from sampled waveform
pulses. The differential circuit is coupled with the sampling-and-holding circuit,
and is configured for extracting a voltage difference of the average waveform pulse.
The integrator circuit is coupled with the differential circuit, and is configured
for performing integration on the average waveform pulse according to the voltage
difference, so as to generate a direct current voltage signal. The voltage-clamping
circuit coupled between the integrator circuit and the illumination lamp. The voltage-clamping
circuit has a threshold voltage level and applies the direct current voltage signal
to the illumination lamp so as to light up the illumination lamp when a level of the
direct current voltage signal exceeds the threshold voltage level of the clamping
circuit.
[0011] According to an embodiment of the invention, the respective waveform pulses of the
dimming signal have a conduction angle, which is adjustable.
[0012] According to an embodiment of the invention, the conduction angle, the level of the
direct current voltage signal is in proportion to a luminance of the illumination
lamp.
[0013] According to an embodiment of the invention, the voltage-clamping circuit blocks
the direct current voltage signal to turn off the illumination lamp when the level
of the direct current voltage signal is below the threshold voltage level of the clamping
circuit.
[0014] Another aspect of the invention is to provide an illumination system coupled with
a household electricity input. The illumination system includes an illumination lamp
and an illumination controlling circuit. The illumination lamp emits light with different
luminance according to an operative current flowing through the illumination lamp.
The illumination controlling circuit is coupled with the household electricity input.
The illumination controlling circuit includes a dimming module, a sampling-and-holding
circuit, a differential circuit, an integrator circuit and a voltage-clamping circuit.
The dimming module is coupled with the household electricity input. The dimming module
is configured for modulating an alternating current input signal from the household
electricity input and generating a dimming signal. The dimming signal includes a plurality
of waveform pulses. The sampling-and-holding circuit is coupled with the dimming module.
The sampling-and-holding circuit is configured to continuously sample the waveform
pulses of the dimming signal to obtain an average waveform pulse from sampled waveform
pulses. The differential circuit is coupled with the sampling-and-holding circuit
configured for extracting a voltage difference of the average waveform pulse. The
integrator circuit is coupled with the differential circuit configured for performing
integration on the average waveform pulse according to the voltage difference, so
as to generate a direct current voltage signal. The voltage-clamping circuit is coupled
between the integrator circuit and the illumination lamp. The voltage-clamping circuit
has a threshold voltage level and applies the direct current voltage signal to the
illumination lamp so as to light up the illumination when a level of the direct current
voltage signal exceeds the threshold voltage level of the clamping circuit. The operative
current flowing through the illumination lamp is correspondingly varied with the level
of the direct current voltage signal.
[0015] According to an embodiment of the invention, the respective waveform pulses of the
dimming signal have a conduction angle, which is adjustable.
[0016] According to an embodiment of the invention, the conduction angle, the level of the
direct current voltage signal is in proportion to a luminance of the illumination
lamp.
[0017] According to an embodiment of the invention, the voltage-clamping circuit blocks
the direct current voltage signal to turn off the illumination lamp when the level
of the direct current voltage signal is below the threshold voltage level of the clamping
circuit.
[0018] According to an embodiment of the invention, the illumination lamp further includes
a switch unit, a lamp driver and a light-emitting load. A first end of the switch
unit is coupled to the voltage-clamping circuit. A second end of the switch unit is
coupled to the light-emitting load. The lamp driver is coupled between a third end
of the switch unit and the light-emitting load. The switch unit selectively couples
the first end to the second end or the third end.
[0019] According to an embodiment of the invention, the switch unit couples the first end
to the second end under a dimming mode for applying the direct current voltage signal
onto the light-emitting load. The switch unit couples the first end to the third end
under a non-dimming mode for applying the direct current voltage signal to the lamp
driver. As such, the lamp driver generates an operative current with a fixed current
value to the light-emitting load.
[0020] It is to be understood that both the foregoing general description and the following
detailed description are by examples, and are intended to provide further explanation
of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The disclosure can be more fully understood by reading the following detailed description
of the embodiments, with reference to the accompanying drawings as follows:
Fig. 1 is a schematic diagram illustrating a dimming signal waveform generated by
a tradition TRIAC dimmer;
Fig. 2 is a function block diagram illustrating an illumination controlling circuit
according to an embodiment of the invention;
Fig. 3 is a waveform diagram illustrating a dimming signal generated by the dimming
module under an ideal condition;
Fig. 4 is a waveform diagram illustrating a dimming signal generated by the dimming
module under a practical condition;
Fig. 5 is a waveform diagram illustrating an average waveform pulse generated by the
sampling-and-holding circuit; and
Fig. 6 is a function block diagram illustrating an illumination system according to
another embodiment of the invention.
DESCRIPTION OF THE EMBODIMENTS
[0022] In an embodiment, the illumination controlling circuit includes a dimming module
for adjusting luminance of an illumination lamp, and it further includes some digital
processing circuit to sample the dimming signals generated by the dimming module and
to generate a stable direct current voltage signal for driving the illumination lamp.
In addition, the illumination controlling circuit has a clamping function. When a
level of the direct current voltage signal is too low, the operative voltage is clamped
to shut down the illumination lamp, so as to prevent the illumination lamp from blinking
or being damaged under low operative voltage.
[0023] In the following description, several specific details are presented to provide a
thorough understanding of the embodiments of the present invention. One skilled in
the relevant art will recognize, however, that the present invention can be practiced
without one or more of the specific details, or in combination with or with other
components, etc. In other instances, well-known implementations or operations are
not shown or described in detail to avoid obscuring aspects of various embodiments
of the present invention.
[0024] Reference is made to Fig. 2, which is a function block diagram illustrating an illumination
controlling circuit 100 according to an embodiment of the invention. As shown in Fig.
2, the illumination controlling circuit 100 is coupled between a household electricity
input 200 and an illumination lamp 220. The illumination controlling circuit 100 includes
a dimming module 120, a sampling-and-holding circuit 140, a differential circuit 160,
an integrator circuit 180 and a voltage-clamping circuit 190.
[0025] The dimming module 120 is coupled with the household electricity input 200. In practical
applications, the household electricity input 200 usually provides an alternating
current (AC) input signal (e.g., 110V/220V AC voltage signal). The dimming module
120 is used to modulate the AC input signal from the household electricity input 200
into a dimming signal. In this embodiment, the dimming module 120 can be a tri-electrode
alternating-current switch (TRIAC) dimmer. The dimming function of the TRIAC dimmer
is realized in a phase-chopping manner. The waveform generated by the TRIAC dimmer
is chopped by its phases. The dimming level is related to a conductive angle in the
phase-chopping process.
[0026] Reference is also made to Fig. 3 and Fig. 4. Fig. 3 is a waveform diagram illustrating
a dimming signal generated by the dimming module 120 under an ideal condition. Fig.
4 is a waveform diagram illustrating a dimming signal generated by the dimming module
120 under a practical condition.
[0027] As shown in Fig. 3 and Fig. 4, each waveform pulse P1, P2, P3 or P4 of the dimming
signal has a conductive angle θ1, θ2, θ3 or θ4. The respective conductive angles θ1,
θ2, θ3 and θ4 of the waveform pulses P1, P2, P3 and P4 are adjustable. For example,
users may rotate a knob of the TRIAC dimmer to adjust the conductive angle for elevating
a brightness level. In this case, the conductive angle will be enlarged for elevating
the brightness level.
[0028] As the ideal condition shown in Fig. 3, the dimming signal generated by the dimming
module 120 includes multiple waveform pulses. As shown in Fig.3, when the dimming
module 120 is configured to a specific brightness level by a user, the waveform pulses
P1, P2, P3 and P4 generated by the dimming module 120 in sequence has an identical
conductive angle. As shown in Fig. 3, the conductive angles of the waveform pulses
P1, P2, P3 and P4 are all equal to the conductive angle θ1.
[0029] However, in practical applications, some tiny differences will exist between the
waveform pulses P1, P2, P3 and P4 generated by the dimming module 120 because of the
limitation of the manufacturing process, even when the dimming level remains unchanged.
As shown in Fig. 4, when the dimming level remains unchanged, the waveform pulses
P1, P2, P3 and P4 in sequence still has different conductive angles, such as the conductive
angles θ1, θ2, θ3 and θ4.
[0030] Reference is made to Fig. 2 and Fig. 4 at the same time, the sampling-and-holding
circuit 140 of the illumination controlling circuit 100 in the embodiment is coupled
to the dimming module 120 and used for sampling from the waveform pulses P1, P2, P3
and P4 of the dimming signal continuously, so as to obtain an average waveform pulse
from sampled waveform pulses.
[0031] For example, in this embodiment, the sampling-and-holding circuit 140 may sample
the waveform pulses P2 and P3 from the waveform pulses shown in Fig. 4 for generating
an average waveform pulse. Reference is also made to Fig. 5, which is a waveform diagram
illustrating an average waveform pulse Pa generated by the sampling-and-holding circuit
140. However, the invention is not limited to sample two waveform pulses in a row.
In another embodiment, the sampling-and-holding circuit 140 may sample three or more
waveform pulses in a row; or in another case, the sampling-and-holding circuit 140
may sample one waveform pulse in every K pulses (K is a positive integer). Accordingly,
the sampling-and-holding circuit 140 may sample the dimming signal generated by the
dimming module 120 and transform the dimming signal into a relatively-steady waveform
state (i.e., the average waveform pulse).
[0032] In the embodiment, the differential circuit 160 is coupled to the sampling-and-holding
circuit 140 for extracting a voltage difference Vd (as shown in Fig. 5) from the average
waveform pulse Pav.
[0033] The integration circuit 180 is coupled with the differential circuit 160. The integration
circuit 180 is used for integrating the sampled average waveform pulse Pav according
to the voltage difference Vd, so as to generate a direct current (DC) voltage signal.
The DC voltage signal can be used for driving the illumination lamp 220 to provide
lights. The luminance of the illumination lamp 220 is higher (i.e., brighter) when
a voltage level of the DC voltage signal is higher, such that the dimming function
is realized.
[0034] Basically, the voltage level of the DC voltage signal is in direct proportion to
the voltage difference Vd of the average waveform pulse Pav. Furthermore, the voltage
level of the DC voltage signal is also in direct proportion to the conduction angle
of the waveform pulses generated by the dimming module 120. In other words, the conduction
angle, the level of the direct current voltage signal and the luminance of the illumination
lamp 220 are in direct proportion. The luminance of the illumination lamp 220 is substantially
decided by the conduction angle of the waveform pulses generated by the dimming module
120.
[0035] In this embodiment, the illumination lamp 220 may include a light-emitting diode
(LED), which has advantages such as photoelectric conversion efficiency, less wasted
heat and long lifetime, etc. However, the LED operated at low driving voltage may
occurs problems including high-frequency blinking, unstable luminance or easy to be
damaged in practical applications. In this embodiment, the illumination lamp 220 can
be a LED lamp (such as product number MR16), but the inventioin is not limited thereto.
[0036] In the embodiment, the illumination controlling circuit 100 includes the voltage-clamping
circuit 190 coupled between the integration circuit 180 and the illumination lamp
220. The voltage-clamping circuit 190 has a threshold voltage level. When a level
of the DC voltage signal exceeds a threshold voltage level of the clamping circuit,
the voltage-clamping circuit 190 conducts the DC voltage signal to the illumination
lamp 220, for driving the illumination lamp 220 to provide lights.
[0037] On the other hand, when the level of the DC voltage signal is below the threshold
voltage level of the clamping circuit 190, the DC voltage signal is blocked by the
voltage-clamping circuit 190, so as to turn off the illumination lamp. For example,
the DC voltage signal is blocked by conducting the DC voltage signal to a ground terminal,
or by turning down the switch located on a conductive path to the illumination lamp
220. In this case, the clamping circuit 190 can turn off the illumination lamp 220
when the DC voltage signal has a low voltage level (below the threshold voltage level),
so as to prevent the LED within the illumination lamp 220 from blicking or being damaged
under low operative voltage.
[0038] Reference is made to Fig. 6, which is a function block diagram illustrating an illumination
system 300 according to another embodiment of the invention.
[0039] As shown in Fig. 6, the illumination system 300 is coupled with a household electricity
input 400. The illumination system includes an illumination lamp 330 and a illumination
controlling circuit 310. The illumination lamp 330 emits light with different luminance
according to an operative current I
L flowing through the illumination lamp 330.
[0040] The illumination controlling circuit 310 is coupled with the household electricity
input 400. The illumination controlling circuit 310 includes a dimming module 320,
a sampling-and-holding circuit 340, a differential circuit 360, an integrator circuit
380 and a voltage-clamping circuit 390. Each module within the illumination controlling
circuit 310 is similar to the illumination controlling circuit 100 in aforesaid embodiment.
The detail descriptions and explanations about these modules in illumination controlling
circuit 310 can be found in the Fig. 2 to Fig. 5 and corresponding paragraphs related
to the illumination controlling circuit 100, and not to be repeated here.
[0041] It is to be noticed that, when the DC voltage signal generated by the integration
circuit 380 exceeds the threshold voltage level of the voltage-clamping circuit 390,
the voltage-clamping circuit 390 conducts the DC voltage signal to the illumination
lamp 330 for driving the illumination lamp 330 to provide lights. The amplitude of
the operative current I
L flowing through the illumination lamp is varied corresponding to the level of the
direct current voltage signal.
[0042] In this embodiment, the conduction angle, the level of the direct current voltage
signal, the amplitude of the operative current I
L and a luminance of the illumination lamp 330 are in direct proportion.
[0043] In addition, the illumination lamp 330 shown in Fig. 6 further includes a switch
unit 332, a lamp driver 334 and a light-emitting load 336. In practical applications,
the light-emitting load 336 can be a light-emitting diode.
[0044] A first end T1 of the switch unit 332 is coupled to the voltage-clamping circuit
390. A second end T2 of the switch unit 332 is coupled to the light-emitting load
336. The lamp driver 334 is coupled between a third end T3 of the switch unit 332
and the light-emitting load 336. The switch unit 332 selectively couples the first
end T1 to the second end T2 or the third end T3.
[0045] In this embodiment, the switch unit 332 couples the first end T1 to the second end
T2 under a dimming mode for applying the direct current voltage signal generated by
the illumination controlling circuit 310 onto the light-emitting load 336. The light-emitting
load 336 emits light at different luminance (brightness) according to the configuration
of the illumination controlling circuit 310.
[0046] In another case, when the dimming function is not required by users (i.e., under
a non-dimming mode), the switch unit 332 couples the first end T1 to the third end
T3 under the non-dimming mode for applying the direct current voltage signal to the
lamp driver 334, and the lamp driver 334 generates an operative current Id with a
fixed current value to the light-emitting load 336. Based on the operative current
Id generated by the lamp driver 334 with fixed current value, the light-emitting load
336 may provide lights at a fixed luminance (brightness), .such that the dimming function
is disabled. In this embodiment, the illumination lamp 330 can be a LED lamp (such
as product number MR16), and the lamp driver 334 can be a built-in lamp driver circuit
of the MR16 LED lamp, but the inventioin is not limited thereto.
[0047] As mentioned in above paragraphs, the disclosure provides an illumination controlling
circuit and an illumination system. In an embodiment, the illumination controlling
circuit includes a dimming module for adjusting luminance of an illumination lamp,
and it further includes some digital processing circuit to sample the dimming signals
generated by the dimming module and to generate a stable direct current voltage signal
for driving the illumination lamp. In addition, the illumination controlling circuit
has a clamping function. When a level of the direct current voltage signal is too
low, the operative voltage is clamped to shut down the illumination lamp, so as to
prevent the illumination lamp from blinking or being damaged under low operative voltage.
1. An illumination controlling circuit, coupled between a household electricity input
and an illumination lamp, the illumination controlling circuit comprising:
a dimming module, coupled with the household electricity input, configured for modulating
an alternating current input signal from the household electricity input and generating
a dimming signal, the dimming signal comprising a plurality of waveform pulses;
a sampling-and-holding circuit, coupled with the dimming module, configured for continuously
sampling the waveform pulses of the dimming signal to obtain an average waveform pulse
from sampled waveform pulses;
a differential circuit, coupled with the sampling-and-holding circuit, configured
for extracting a voltage difference of the average waveform pulse;
an integrator circuit, coupled with the differential circuit, configured for performing
integration on the average waveform pulse according to the voltage difference, so
as to generate a direct current voltage signal; and
a voltage-clamping circuit, coupled between the integrator circuit and the illumination
lamp, having a threshold voltage level, the voltage-clamping circuit applying the
direct current voltage signal to the illumination lamp so as to light up the illumination
lamp when a level of the direct current voltage signal exceeds the threshold voltage
level of the clamping circuit.
2. The illumination controlling circuit as claimed in claim 1, wherein the respective
waveform pulses of the dimming signal have a conduction angle which is adjustable.
3. The illumination controlling circuit as claimed in claim 2, wherein the conduction
angle, the level of the direct current voltage signal is in proportion to a luminance
of the illumination lamp.
4. The illumination controlling circuit as claimed in claim 1, wherein the voltage-clamping
circuit blocks the direct current voltage signal to turn off the illumination lamp
when the level of the direct current voltage signal is below the threshold voltage
level of the clamping circuit.
5. An illumination system, coupled with a household electricity input, the illumination
system comprising:
an illumination lamp emitting light with a luminance according to an operative current
flowing through the illumination lamp; and
an illumination controlling circuit, coupled with the household electricity input,
the illumination controlling circuit comprising:
a dimming module, coupled with the household electricity input, configured for modulating
an alternating current input signal from the household electricity input and generating
a dimming signal, the dimming signal comprising a plurality of waveform pulses;
a sampling-and-holding circuit, coupled with the dimming module, configured for continuously
sampling the waveform pulses of the dimming signal to obtain an average waveform pulse
from sampled waveform pulses;
a differential circuit, coupled with the sampling-and-holding circuit, configured
for extracting a voltage difference of the average waveform pulse;
an integrator circuit, coupled with the differential circuit, configured for performing
integration on the average waveform pulse according to the voltage difference, so
as to generate a direct current voltage signal; and
a voltage-clamping circuit, coupled between the integrator circuit and the illumination
lamp, having a threshold voltage level, the voltage-clamping circuit applying the
direct current voltage signal to the illumination lamp so as to light up the illumination
lamp when a level of the direct current voltage signal exceeds the threshold voltage
level of the clamping circuit, wherein the operative current flowing through the illumination
lamp is correspondingly varied with the level of the direct current voltage signal.
6. The illumination system as claimed in claim 5, wherein the respective waveform pulses
of the dimming signal have a conduction angle which is adjustable.
7. The illumination system as claimed in claim 6, wherein the conduction angle, the level
of the direct current voltage signal is in proportion to a luminance of the illumination
lamp.
8. The illumination system as claimed in claim 5, wherein the voltage-clamping circuit
blocks the direct current voltage to turn off the illumination lamp when the level
of the direct current voltage signal is below the threshold voltage level of the clamping
circuit.
9. The illumination system as claimed in claim 5, wherein the illumination lamp further
comprises a switch unit, a lamp driver and a light-emitting load, wherein a first
end of the switch unit is coupled to the voltage-clamping circuit; a second end of
the switch unit is coupled to the light-emitting load; the lamp driver is coupled
between a third end of the switch unit and the light-emitting load; and the switch
unit selectively couples the first end to the second end or the third end.
10. The illumination system as claimed in claim 9, wherein the switch unit, under a dimming
mode, couples the first end to the second end for applying the direct current voltage
signal onto the light-emitting load, and the switch unit, under a non-dimming mode,
couples the first end to the third end for applying the direct current voltage signal
to the lamp driver, such that the lamp driver generates an operative current with
a fixed current value to the light-emitting load.